Common Shares Withheld Upon Vesting

No definition available.

Name:	psb_CommonSharesWithheldUponVesting
Namespace Prefix:	psb_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Possible Target Award Adjustment Based on Strategic and Operational Accomplishments

+ References

No definition available.

+ Details

Name:	psb_ShareBasedCompensationArrangementByShareBasedPaymentAward
Namespace Prefix:	psb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of annual vesting installments.

+ References

No definition available.

+ Details

Name:	psb_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAnnualInstallments
Namespace Prefix:	psb_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_AllocatedShareBasedCompensationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cash paid to settle liability for award under share-based payment arrangement.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of vesting of award under share-based payment arrangement.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number, after forfeiture, of shares or units issued under share-based payment arrangement. Excludes shares or units issued under employee stock ownership plan (ESOP).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of share options (or share units) exercised during the current period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(2)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Value of stock related to Restricted Stock Awards issued during the period, net of the stock value of such awards forfeited.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

+ Details

Name:	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=psb_StockOptionsAndRestrictedStockUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_TitleOfIndividualAxis=psb_PresidentAndChiefExecutiveOfficerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=psb_CertainRestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=psb_ShareBasedCompensationAwardTrancheFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=psb_ShareBasedCompensationAwardTrancheFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=psb_ShareBasedCompensationAwardTrancheSixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VestingAxis=us-gaap_ShareBasedCompensationAwardTrancheOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=psb_IncentiveProgram2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=psb_RetirementPlanForNonEmployeeDirectorsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_TitleOfIndividualAxis=srt_DirectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Stock Compensation (Narrative) (Details) $ in Thousands	1 Months Ended	3 Months Ended		7 Months Ended	9 Months Ended
Stock Compensation (Narrative) (Details) $ in Thousands	Apr. 30, 2019 USD ($) shares	Sep. 30, 2020 USD ($) shares	Sep. 30, 2019 USD ($) shares	Jul. 31, 2019 shares	Sep. 30, 2020 USD ($) item shares	Sep. 30, 2019 USD ($) shares	Dec. 31, 2019 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash paid for taxes in lieu of shares upon vesting of restricted stock units \| $		$ 442	$ 620		$ 4,102	$ 6,120
Stock Options and Restricted Stock Units [Member] \| President and CEO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $		$ 1,700			$ 1,700
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period					10 years
Options exercised					4,136
Options forfeited					0
Options outstanding		171,694			171,694		157,830
Stock units granted					18,000
Compensation expense \| $		$ 100	100		$ 300	$ 200
Restricted Stock Units (RSUs) Granted Prior To 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					6 years
Restricted Stock Units (RSUs) Granted Prior To 2016 [Member] \| Year Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					20.00%
Restricted Stock Units (RSUs) Granted Prior To 2016 [Member] \| Year Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					20.00%
Restricted Stock Units (RSUs) Granted Prior To 2016 [Member] \| Year Four [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					20.00%
Restricted Stock Units (RSUs) Granted Prior To 2016 [Member] \| Year Five [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					20.00%
Restricted Stock Units (RSUs) Granted Prior To 2016 [Member] \| Year Six [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					20.00%
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					5 years
Stock units granted					100
Issuance of common stock in connection with stock-based compensation, shares					41,699	53,859
Stock units vested					70,576
Stock units forfeited					1,920
Common shares withheld upon vesting					28,877	38,961
Awards outstanding		78,452			78,452		150,848
Compensation expense \| $		$ 2,200	800		$ 3,500	$ 2,500
Restricted Stock Units (RSUs) [Member] \| Year One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					20.00%
Restricted Stock Units (RSUs) [Member] \| Year Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					20.00%
Restricted Stock Units (RSUs) [Member] \| Year Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					20.00%
Restricted Stock Units (RSUs) [Member] \| Year Four [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					20.00%
Restricted Stock Units (RSUs) [Member] \| Year Five [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage					20.00%
2020 Incentive Program [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of annual vesting installments \| item					5
Retirement Plan for Non-Employee Directors [Member] \| Restricted Stock Units (RSUs) [Member] \| Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock in connection with stock-based compensation, shares	8,000				0
Compensation expense \| $		$ 200	$ 1,200		$ 600	$ 1,300
Aggregate fair value of the shares issued \| $	$ 1,200
Minimum [Member] \| 2020 Incentive Program [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Possible target award adjustment based on strategic and operational accomplishments					75.00%
Maximum [Member] \| 2020 Incentive Program [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Possible target award adjustment based on strategic and operational accomplishments					125.00%
Maximum [Member] \| Retirement Plan for Non-Employee Directors [Member] \| Restricted Stock Units (RSUs) [Member] \| Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock in connection with stock-based compensation, shares			10,000	8,000